Airlines in the United States, South Korea and Japan have grounded dozens of Boeing 777 aircraft after one of the jets suffered engine failure Saturday, sending debris crashing down over Denver.
Boeing () on Sunday recommended that airlines stop flying versions of the aircraft that are equipped with Pratt & Whitney 4000-112 engines while US authorities investigate the Denver incident.
The plane manufacturer said that 69 of the 777 jets that are in service are powered by the engine, while 59 such aircraft are in storage.
United Airlines (), Korean Air, Asiana Airlines, All Nippon Airways and Japan Airlines ( ) all use Boeing 777s that feature Pratt & Whitney 4000 engines.
The groundings come after an engine attached to a United-operated 777 plane failed Saturday, just minutes after the Honolulu-bound flight took off from Denver International Airport. As United Flight 328 returned to the airport, it dropped more engine debris through the roofs of homes and into yards.
An initial examination of the Pratt & Whitney PW4077 engine from that flight showed that two fan blades were fractured, according to the US National Transportation Safety Board (NTSB). The agency said that the remaining blades exhibited damage “to the tips and leading edges.”
The findings are preliminary, but they were still enough to spur some airlines to pull planes that use those types of engines from service. The NTSB said that it will examine the engine, airline and photos and videos taken by passengers on board the flight, along with the flight data and cockpit voice recorders.
Investigators believe a fan blade in the engine came off and took out another blade, a source familiar with the situation told CNN.
United said Sunday that it would immediately pull 24 planes from flying “out of an abundance of caution.” The company said its move was voluntary and temporary and should disrupt only “a small number of customers.”
Japan’s transportation ministry, meanwhile, said that it had ordered All Nippon Airways and Japan Airlines to ground planes using that series of engines. The ministry said that order applied to 19 Boeing 777s at All Nippon Airways and 13 at Japan Airlines that have Prat & Whitney 4000 engines.
South Korea’s Asiana Airlines, which owns nine of the planes, said it would stop using them, too.
The jets are also used by Korean Air, which on Tuesday said it would ground the planes. The airline has six of the jets in service, while 10 are in storage.
According to the most recent registry data, the only airlines that operate with the affected engines are in the United States, Japan and South Korea. United is the only US operator with this type of engine in its fleet.